Classes
struct	EchoState_
	Internal echo canceller state structure. More...

struct	fft_state< Allocator >
	FFT state management structure with custom allocator support. More...

class	MDFEchoCancellation< Allocator >
	Acoustic echo canceller using MDF algorithm. More...

Typedefs
typedef struct EchoState_	EchoState

using	FloatAllocator = typename std::allocator_traits< Allocator >::template rebind_alloc< float >

Functions
constexpr	echo_float_t (int16_t mantissa=0, int16_t exponent=0)

	fft_state (int size, AudioFFTBase *drv, const Allocator &alloc=Allocator())
	Construct FFT state with specified size and driver.

	MDFEchoCancellation (int filterLength, AudioFFTBase &fftDriver, const Allocator &alloc=Allocator())

	MDFEchoCancellation (int filterLength, int nbMic, int nbSpeakers, AudioFFTBase &fftDriver, const Allocator &alloc=Allocator())

	~MDFEchoCancellation ()

void	cancel (const echo_int16_t rec, const echo_int16_t play, echo_int16_t *out)

void	capture (const echo_int16_t rec, echo_int16_t out)

int	control (int request, void *ptr)

template<typename Allocator = std::allocator<uint8_t>>
void	echo_fft (void table, echo_word16_t in, echo_word16_t *out)
	Perform forward FFT.

template<typename Allocator = std::allocator<uint8_t>>
void	echo_fft_destroy (void *table)
	Destroy FFT state and release resources.

template<typename Allocator >
void *	echo_fft_init (int size, AudioFFTBase *driver, const Allocator &alloc)
	Initialize FFT state.

template<typename Allocator = std::allocator<uint8_t>>
void	echo_ifft (void table, echo_word16_t in, echo_word16_t *out)
	Perform inverse FFT.

template<typename T >
T *	echoAlloc (size_t count)
	Allocate memory for array of type T using custom allocator.

void	echoCancellationImpl (EchoState st, const echo_int16_t in, const echo_int16_t far_end, echo_int16_t out)
	Core echo cancellation implementation.

void	echoFatal (const char *str)

template<typename T >
void	echoFree (T *ptr, size_t count=0)
	Deallocate memory using custom allocator.

EchoState *	echoStateInitMc (int frame_size, int filter_length, int nb_mic, int nb_speakers)
	Initialize multi-channel echo canceller state.

void	echoWarning (const char *str)

void	ensureInitialized ()
	Ensure echo canceller is initialized (lazy initialization)

void	filterDcNotch16 (const echo_int16_t in, echo_word16_t radius, echo_word16_t out, int len, echo_mem_t *mem, int stride)
	Apply DC notch filter to remove DC offset.

int	getFilterLength ()

int	getFrameSize ()

void	getImpulseResponse (echo_int32_t *response)

int	getImpulseResponseSize ()

int	getMicChannels ()

int	getSamplingRate ()

int	getSpeakerChannels ()

EchoState *	getState ()

void	mdfAdjustProp (const echo_word32_t W, int N, int M, int P, echo_word16_t prop)
	Adjust proportional adaptation weights.

echo_word32_t	mdfInnerProd (const echo_word16_t x, const echo_word16_t y, int len)
	Compute inner product of two vectors.

echo_float_t	operator* (const echo_float_t &other) const

echo_word32_t	operator* (int16_t scalar) const

echo_word32_t	operator* (int32_t scalar) const

void	playback (const echo_int16_t *play)

void	powerSpectrum (const echo_word16_t X, echo_word32_t ps, int N)
	Compute power spectrum from FFT output.

void	powerSpectrumAccum (const echo_word16_t X, echo_word32_t ps, int N)
	Accumulate power spectrum from FFT output.

void	reset ()

void	setFFTDriver (AudioFFTBase &fftDriver)

void	setFilterLength (int len)

void	setMicChannels (int num)

void	setSamplingRate (int rate)

void	setSpeakerChannels (int num)

void	spectralMulAccum (const echo_word16_t X, const echo_word32_t Y, echo_word16_t *acc, int N, int M)
	Accumulate spectral multiplication across multiple frames.

float	spxCos (float x)
	Compute cosine function.

float	spxExp (float x)
	Compute exponential function.

echo_int16_t	spxIlog2 (echo_uint32_t x)

float	spxSqrt (float x)

void	weightedSpectralMulConj (const echo_float_t w, const echo_float_t p, const echo_word16_t X, const echo_word16_t Y, echo_word32_t prod, int N)
	Compute weighted spectral multiplication with conjugate.

Variables
int	adapted

Allocator	allocator

echo_word16_t	beta0

echo_word16_t	beta_max

int	C

int	cancel_count

echo_word32_t	Davg1

echo_word32_t	Davg2

AudioFFTBase *	driver

echo_float_t	Dvar1

echo_float_t	Dvar2

int16_t	e

echo_word16_t *	e

echo_word16_t *	E

echo_word32_t *	Eh

AudioFFTBase *	fft_driver

void *	fft_table

int	filter_length

echo_word16_t *	foreground

int	frame_size

bool	initialized = false

echo_word16_t *	input

int	K

echo_word16_t *	last_y

echo_word16_t	leak_estimate

int16_t	m

int	M

echo_word16_t *	memD

echo_word16_t *	memE

echo_word16_t *	memX

int	N

int	nb_mic

int	nb_speakers

echo_mem_t *	notch_mem

echo_word16_t	notch_radius

echo_float_t	Pey

echo_word32_t *	PHI

echo_int16_t *	play_buf

int	play_buf_pos

int	play_buf_started

echo_word32_t *	power

echo_float_t *	power_1

echo_word16_t	preemph

echo_word16_t *	prop

echo_float_t	Pyy

echo_word32_t *	Rf

echo_int32_t	sampling_rate

int	saturated

int	screwed_up

echo_word16_t	spec_average

EchoState *	state = nullptr

echo_word32_t	sum_adapt

std::vector< float, FloatAllocator >	temp_img

std::vector< float, FloatAllocator >	temp_real

echo_word32_t *	W

echo_word16_t *	window

int	window_size

echo_word16_t *	wtmp

echo_word16_t *	x

echo_word16_t *	X

echo_word32_t *	Xf

echo_word16_t *	y

echo_word16_t *	Y

echo_word32_t *	Yf

echo_word32_t *	Yh

Friends
echo_word32_t	operator* (int32_t scalar, const echo_float_t &f)

Detailed Description

This is the acoustic echo canceller module.

Typedef Documentation

◆ FloatAllocator

template<typename Allocator = std::allocator<uint8_t>>

using FloatAllocator = typename std::allocator_traits<Allocator>::template rebind_alloc<float>

Rebound allocator for float vectors

Function Documentation

◆ fft_state()

template<typename Allocator = std::allocator<uint8_t>>

fft_state	(	int	size,
		AudioFFTBase *	drv,
		const Allocator &	alloc = `Allocator()`
	)

inline

Construct FFT state with specified size and driver.

Parameters

size	FFT size (number of points)
drv	Pointer to FFT driver implementation
alloc	Allocator instance for memory management

◆ MDFEchoCancellation() [1/2]

template<typename Allocator = std::allocator<uint8_t>>

MDFEchoCancellation	(	int	filterLength,
		AudioFFTBase &	fftDriver,
		const Allocator &	alloc = `Allocator()`
	)

inline

Initialize echo canceller with single channel (mono)

Parameters

filterLength	Length of echo cancellation filter in samples
fftDriver	FFT driver instance from AudioFFT
alloc	Allocator instance (optional)

◆ MDFEchoCancellation() [2/2]

template<typename Allocator = std::allocator<uint8_t>>

MDFEchoCancellation	(	int	filterLength,
		int	nbMic,
		int	nbSpeakers,
		AudioFFTBase &	fftDriver,
		const Allocator &	alloc = `Allocator()`
	)

inline

Initialize echo canceller with multiple channels

Parameters

filterLength	Length of echo cancellation filter in samples
nbMic	Number of microphone channels
nbSpeakers	Number of speaker channels
fftDriver	FFT driver instance from AudioFFT
alloc	Allocator instance (optional)

◆ ~MDFEchoCancellation()

template<typename Allocator = std::allocator<uint8_t>>

~MDFEchoCancellation ( )

inline

Destructor

◆ cancel()

template<typename Allocator = std::allocator<uint8_t>>

void cancel	(	const echo_int16_t *	rec,
		const echo_int16_t *	play,
		echo_int16_t *	out
	)

inline

Perform echo cancellation

Parameters

rec	Recorded signal (with echo)
play	Playback signal (reference)
out	Output signal (echo removed)

◆ capture()

template<typename Allocator = std::allocator<uint8_t>>

void capture	(	const echo_int16_t *	rec,
		echo_int16_t *	out
	)

inline

Process captured audio with buffered playback

Parameters

rec	Recorded signal
out	Output signal (echo removed)

◆ control()

template<typename Allocator = std::allocator<uint8_t>>

int control	(	int	request,
		void *	ptr
	)

inline

Control/query echo canceller parameters

Parameters

request	Request type (ECHO_GET_FRAME_SIZE, etc.)
ptr	Pointer to parameter value

Returns: 0 on success, -1 on error

◆ echo_fft()

template<typename Allocator = std::allocator<uint8_t>>

void echo_fft	(	void *	table,
		echo_word16_t *	in,
		echo_word16_t *	out
	)

inline

Perform forward FFT.

Template Parameters

Allocator Custom allocator type (must match the one used in echo_fft_init)

Parameters

table	Opaque pointer to FFT state
in	Input time-domain signal (size N)
out	Output frequency-domain signal in packed format (size N) Format: [DC, real1, imag1, real2, imag2, ..., Nyquist]

◆ echo_fft_destroy()

template<typename Allocator = std::allocator<uint8_t>>

void echo_fft_destroy ( void * table )

inline

Destroy FFT state and release resources.

Template Parameters

Allocator Custom allocator type (must match the one used in echo_fft_init)

Parameters

table Opaque pointer to FFT state returned by echo_fft_init

◆ echo_fft_init()

template<typename Allocator >

void * echo_fft_init	(	int	size,
		AudioFFTBase *	driver,
		const Allocator &	alloc
	)

inline

Initialize FFT state.

Template Parameters

Allocator Custom allocator type for memory management

Parameters

size	FFT size (number of points)
driver	Pointer to FFT driver implementing AudioFFTBase interface
alloc	Allocator instance for memory management

Returns: Opaque pointer to FFT state, or nullptr on failure

◆ echo_ifft()

template<typename Allocator = std::allocator<uint8_t>>

void echo_ifft	(	void *	table,
		echo_word16_t *	in,
		echo_word16_t *	out
	)

inline

Perform inverse FFT.

Template Parameters

Allocator Custom allocator type (must match the one used in echo_fft_init)

Parameters

table	Opaque pointer to FFT state
in	Input frequency-domain signal in packed format (size N) Format: [DC, real1, imag1, real2, imag2, ..., Nyquist]
out	Output time-domain signal (size N)

◆ echoAlloc()

template<typename Allocator = std::allocator<uint8_t>>

template<typename T >

T * echoAlloc ( size_t count )

inlineprotected

Allocate memory for array of type T using custom allocator.

Template Parameters

T	Type of objects to allocate

Parameters

count Number of objects to allocate

Returns: Pointer to allocated and zero-initialized memory

Note: Memory is zero-initialized to match calloc behavior

◆ echoCancellationImpl()

template<typename Allocator = std::allocator<uint8_t>>

void echoCancellationImpl	(	EchoState *	st,
		const echo_int16_t *	in,
		const echo_int16_t *	far_end,
		echo_int16_t *	out
	)

inlineprotected

Core echo cancellation implementation.

Implements the complete MDF echo cancellation algorithm including:

Pre-processing (DC notch filter, pre-emphasis)
FFT transformation of input signals
Adaptive filter update in frequency domain
Echo prediction and subtraction
Two-path filter switching for double-talk handling
Post-processing (de-emphasis)

Parameters

st	Echo state structure containing all internal state
in	Input signal from microphones (interleaved if multi-channel)
far_end	Reference signal from speakers (interleaved if multi-channel)
out	Output signal with echo removed (interleaved if multi-channel)

◆ echoFree()

template<typename Allocator = std::allocator<uint8_t>>

template<typename T >

void echoFree	(	T *	ptr,
		size_t	count = `0`
	)

inlineprotected

Deallocate memory using custom allocator.

Template Parameters

T	Type of objects to deallocate

Parameters

ptr	Pointer to memory to deallocate
count	Number of objects (currently unused but kept for API compatibility)

Note: For POD types used in speexdsp, count parameter is not strictly required

◆ echoStateInitMc()

template<typename Allocator = std::allocator<uint8_t>>

EchoState * echoStateInitMc	(	int	frame_size,
		int	filter_length,
		int	nb_mic,
		int	nb_speakers
	)

inlineprotected

Initialize multi-channel echo canceller state.

Parameters

frame_size	Number of samples per frame
filter_length	Total filter length in samples
nb_mic	Number of microphone channels
nb_speakers	Number of speaker channels

Returns: Pointer to initialized echo state, or nullptr on failure

◆ filterDcNotch16()

template<typename Allocator = std::allocator<uint8_t>>

void filterDcNotch16	(	const echo_int16_t *	in,
		echo_word16_t	radius,
		echo_word16_t *	out,
		int	len,
		echo_mem_t *	mem,
		int	stride
	)

inlineprotected

Apply DC notch filter to remove DC offset.

Parameters

in	Input signal
radius	Filter radius parameter
out	Output filtered signal
len	Length of signal
mem	Filter memory state (2 values)
stride	Stride for accessing input array

◆ getFilterLength()

template<typename Allocator = std::allocator<uint8_t>>

int getFilterLength ( )

inline

Get filter length

◆ getFrameSize()

template<typename Allocator = std::allocator<uint8_t>>

int getFrameSize ( )

inline

Get frame size

◆ getImpulseResponse()

template<typename Allocator = std::allocator<uint8_t>>

void getImpulseResponse ( echo_int32_t * response )

inline

Get impulse response

Parameters

response Buffer to store impulse response (must be pre-allocated)

◆ getImpulseResponseSize()

template<typename Allocator = std::allocator<uint8_t>>

int getImpulseResponseSize ( )

inline

Get impulse response size

◆ getMicChannels()

template<typename Allocator = std::allocator<uint8_t>>

int getMicChannels ( )

inline

Get number of microphone channels

◆ getSamplingRate()

template<typename Allocator = std::allocator<uint8_t>>

int getSamplingRate ( )

inline

Get sampling rate

◆ getSpeakerChannels()

template<typename Allocator = std::allocator<uint8_t>>

int getSpeakerChannels ( )

inline

Get number of speaker channels

◆ getState()

template<typename Allocator = std::allocator<uint8_t>>

EchoState * getState ( )

inline

Get underlying state (for advanced usage)

◆ mdfAdjustProp()

template<typename Allocator = std::allocator<uint8_t>>

void mdfAdjustProp	(	const echo_word32_t *	W,
		int	N,
		int	M,
		int	P,
		echo_word16_t *	prop
	)

inlineprotected

Adjust proportional adaptation weights.

Parameters

W	Filter weights in frequency domain
N	FFT size
M	Number of filter blocks
P	Number of channels
prop	Output proportional weights (normalized)

◆ mdfInnerProd()

template<typename Allocator = std::allocator<uint8_t>>

echo_word32_t mdfInnerProd	(	const echo_word16_t *	x,
		const echo_word16_t *	y,
		int	len
	)

inlineprotected

Compute inner product of two vectors.

Parameters

x	First input vector
y	Second input vector
len	Length of vectors

Returns: Sum of element-wise products

◆ playback()

template<typename Allocator = std::allocator<uint8_t>>

void playback ( const echo_int16_t * play )

inline

Buffer playback signal for later processing

Parameters

play	Playback signal to buffer

◆ powerSpectrum()

template<typename Allocator = std::allocator<uint8_t>>

void powerSpectrum	(	const echo_word16_t *	X,
		echo_word32_t *	ps,
		int	N
	)

inlineprotected

Compute power spectrum from FFT output.

Parameters

X	FFT output in packed format
ps	Output power spectrum
N	FFT size

◆ powerSpectrumAccum()

template<typename Allocator = std::allocator<uint8_t>>

void powerSpectrumAccum	(	const echo_word16_t *	X,
		echo_word32_t *	ps,
		int	N
	)

inlineprotected

Accumulate power spectrum from FFT output.

Parameters

X	FFT output in packed format
ps	Accumulated power spectrum (updated in place)
N	FFT size

◆ reset()

template<typename Allocator = std::allocator<uint8_t>>

void reset ( )

inline

Reset echo canceller state

◆ setFFTDriver()

template<typename Allocator = std::allocator<uint8_t>>

void setFFTDriver ( AudioFFTBase & fftDriver )

inline

Set FFT driver (must be called before first use)

Parameters

fftDriver Reference to FFT driver instance

◆ setFilterLength()

template<typename Allocator = std::allocator<uint8_t>>

void setFilterLength ( int len )

inline

Set filter length (must be called before first use)

Parameters

len	Length of echo cancellation filter in samples

◆ setMicChannels()

template<typename Allocator = std::allocator<uint8_t>>

void setMicChannels ( int num )

inline

Set number of microphone channels (must be called before first use)

Parameters

num	Number of microphone channels

◆ setSamplingRate()

template<typename Allocator = std::allocator<uint8_t>>

void setSamplingRate ( int rate )

inline

Set sampling rate

Parameters

rate	Sampling rate in Hz

◆ setSpeakerChannels()

template<typename Allocator = std::allocator<uint8_t>>

void setSpeakerChannels ( int num )

inline

Set number of speaker channels (must be called before first use)

Parameters

num	Number of speaker channels

◆ spectralMulAccum()

template<typename Allocator = std::allocator<uint8_t>>

void spectralMulAccum	(	const echo_word16_t *	X,
		const echo_word32_t *	Y,
		echo_word16_t *	acc,
		int	N,
		int	M
	)

inlineprotected

Accumulate spectral multiplication across multiple frames.

Parameters

X	Input spectrum (M frames)
Y	Filter weights in frequency domain
acc	Output accumulated result
N	FFT size
M	Number of frames to accumulate

◆ spxCos()

template<typename Allocator = std::allocator<uint8_t>>

float spxCos ( float x )

inlineprotected

Compute cosine function.

Parameters

x	Input angle in radians

Returns: Cosine of x

◆ spxExp()

template<typename Allocator = std::allocator<uint8_t>>

float spxExp ( float x )

inlineprotected

Compute exponential function.

Parameters

x	Input value

Returns: e raised to the power of x

◆ weightedSpectralMulConj()

template<typename Allocator = std::allocator<uint8_t>>

void weightedSpectralMulConj	(	const echo_float_t *	w,
		const echo_float_t	p,
		const echo_word16_t *	X,
		const echo_word16_t *	Y,
		echo_word32_t *	prod,
		int	N
	)

inlineprotected

Compute weighted spectral multiplication with conjugate.

Parameters

w	Weight array for each frequency bin
p	Global scaling factor
X	First input spectrum
Y	Second input spectrum (conjugated)
prod	Output product
N	FFT size

Variable Documentation

◆ allocator

template<typename Allocator = std::allocator<uint8_t>>

Allocator allocator

protected

Allocator instance for memory management

◆ driver

template<typename Allocator = std::allocator<uint8_t>>

AudioFFTBase* driver

Pointer to FFT driver implementation

◆ fft_driver

template<typename Allocator = std::allocator<uint8_t>>

AudioFFTBase* fft_driver

protected

Pointer to FFT driver instance

◆ filter_length

template<typename Allocator = std::allocator<uint8_t>>

int filter_length

protected

Length of echo cancellation filter

◆ frame_size

int frame_size

Number of samples processed each time

◆ initialized

template<typename Allocator = std::allocator<uint8_t>>

bool initialized = false

protected

Lazy initialization flag

◆ K

int K

Number of input channels (microphones)

◆ N

template<typename Allocator = std::allocator<uint8_t>>

int N

FFT size

◆ nb_mic

template<typename Allocator = std::allocator<uint8_t>>

int nb_mic

protected

Number of microphone channels

◆ nb_speakers

template<typename Allocator = std::allocator<uint8_t>>

int nb_speakers

protected

Number of speaker channels

◆ sampling_rate

echo_int32_t sampling_rate

Number of output channels (loudspeakers)

◆ state

template<typename Allocator = std::allocator<uint8_t>>

EchoState* state = nullptr

protected

Pointer to internal echo canceller state

◆ temp_img

template<typename Allocator = std::allocator<uint8_t>>

std::vector<float, FloatAllocator> temp_img

Temporary buffer for imaginary components

◆ temp_real

template<typename Allocator = std::allocator<uint8_t>>

std::vector<float, FloatAllocator> temp_real

Temporary buffer for real components

Classes

Typedefs

Functions

Variables

Friends

Detailed Description

Typedef Documentation

◆ FloatAllocator

Function Documentation

◆ fft_state()

◆ MDFEchoCancellation() [1/2]

◆ MDFEchoCancellation() [2/2]

◆ ~MDFEchoCancellation()

◆ cancel()

◆ capture()

◆ control()

◆ echo_fft()

◆ echo_fft_destroy()

◆ echo_fft_init()

◆ echo_ifft()

◆ echoAlloc()

◆ echoCancellationImpl()

◆ echoFree()

◆ echoStateInitMc()

◆ filterDcNotch16()

◆ getFilterLength()

◆ getFrameSize()

◆ getImpulseResponse()

◆ getImpulseResponseSize()

◆ getMicChannels()

◆ getSamplingRate()

◆ getSpeakerChannels()

◆ getState()

◆ mdfAdjustProp()

◆ mdfInnerProd()

◆ playback()

◆ powerSpectrum()

◆ powerSpectrumAccum()

◆ reset()

◆ setFFTDriver()

◆ setFilterLength()

◆ setMicChannels()

◆ setSamplingRate()

◆ setSpeakerChannels()

◆ spectralMulAccum()

◆ spxCos()

◆ spxExp()

◆ weightedSpectralMulConj()

Variable Documentation

◆ allocator

◆ driver

◆ fft_driver

◆ filter_length

◆ frame_size

◆ initialized

◆ K

◆ N

◆ nb_mic

◆ nb_speakers

◆ sampling_rate

◆ state

◆ temp_img

◆ temp_real